doc: add defaults option example to cluster documentation

[yangbodong22011]

Description

Describe your pull request here

Add defaults option example to cluster documentation, see #1719 (comment)

Checklist

• Does npm test pass with this change (including linting)?
• Is the new or changed code fully tested?
• Is a documentation update included (if this change modifies existing APIs, or introduces new ones)?

[yangbodong22011]

@leibale Please have a look when you have time. It did take me quite a while to find the correct configuration, and I haven't been able to find documentation that already exists.

[codecov-commenter]

Codecov Report

Base: 95.85% // Head: 90.91% // Decreases project coverage by -4.95% ⚠️

Coverage data is based on head (533ee71) compared to base (c5b6f77).
Patch has no changes to coverable lines.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2377      +/-   ##
==========================================
- Coverage   95.85%   90.91%   -4.95%     
==========================================
  Files         449      451       +2     
  Lines        4224     4247      +23     
  Branches      471      475       +4     
==========================================
- Hits         4049     3861     -188     
- Misses        107      314     +207     
- Partials       68       72       +4     

Impacted Files	Coverage Δ
packages/client/lib/commands/FUNCTION_LOAD.ts	16.66% <0.00%> (-83.34%)	⬇️
packages/client/lib/commands/ZRANGESTORE.ts	20.00% <0.00%> (-80.00%)	⬇️
packages/client/lib/commands/FUNCTION_FLUSH.ts	20.00% <0.00%> (-80.00%)	⬇️
packages/client/lib/commands/FUNCTION_RESTORE.ts	20.00% <0.00%> (-80.00%)	⬇️
packages/client/lib/commands/GETEX.ts	21.42% <0.00%> (-78.58%)	⬇️
packages/client/lib/commands/COPY.ts	33.33% <0.00%> (-66.67%)	⬇️
packages/client/lib/commands/CLIENT_NO-EVICT.ts	33.33% <0.00%> (-66.67%)	⬇️
packages/client/lib/commands/ZINTER.ts	36.36% <0.00%> (-63.64%)	⬇️
packages/client/lib/commands/GEOSEARCHSTORE.ts	36.36% <0.00%> (-63.64%)	⬇️
packages/client/lib/commands/FUNCTION_LIST.ts	37.50% <0.00%> (-62.50%)	⬇️
... and 68 more

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